A printer is known which receives printing data together with a state inquiry signal from a host computer and returns a state response signal representing a printing end state to the host computer after performing a printing process. This kind of printer prints the printing data received from the host computer and transmits the response signal representing the printing end state to the host computer. Since the host computer checks the response signal and then transmits printing data for the next row, there is a time interval between the printing for the previous row and the printing for the next row. As a result, there is a problem in that the printing process may not be continuously performed and may not be efficiently performed as a whole.
Furthermore, a method is known which controls a line printer including a printer control unit for pre-fetching a command from an upper-level apparatus and notifying a paper-out condition to the upper-level apparatus when detecting a state where the paper almost runs out. However, this method merely notifies the paper-out condition to the upper-level apparatus before the paper runs out.